It was 50 years ago this Friday, on Feb. 10, 1967, that the state of Nevada became the 38th to ratify the 25th Amendment, thereby officially answering a question that had plagued the United States ever since its founding. How could the country make sure that there would always be a capable person at the helm of the ship of state? If the President were killed, the answer was clear; if he were sick or injured, however, the Constitution was vague.
President Johnson, who had come to the White House under extraordinary circumstances following the assassination of John F. Kennedy in 1963, knew that the time had come for a solution to be put in place. In January of 1965, he had sent a message to Congress noting that it was largely luck alone that the U.S. could thank for thus far avoiding a catastrophic situation in which a President was incapacitated but not dead. Following a run of other officials who had suggested the same, he called for a Constitutional amendment that would address the matter.
“On at least two occasions in our history, and perhaps others, American presidents—James Garfield and Woodrow Wilson—have for prolonged periods been rendered incapable of discharging their Presidential duties,” he wrote. “On sixteen occasions in our thirty-six Administrations, the Office of Vice President has been vacant—and over the two perilous decades since the end of the Second World War, that vital office has been vacant the equivalent of one year out of four.” (He also noted that the Constitution did not provide for the possibility of subversion of the Electoral College as a possible problem with Presidential succession.)
As TIME noted, the amendment came amidst a flurry of tweaks to the Constitution, during which residents of Washington, D.C., got the vote in Presidential elections and poll taxes were banned. The 25th Amendment as it eventually passed did not take on all of Johnson’s suggestions, but it strove to address his top two concerns, as the magazine summed up the week of its ratification:
Under the amendment, an incapacitated Chief Executive can himself declare in writing that he is unable to continue in office, and the Vice President can take over—at least temporarily. If an ailing President is unable or unwilling to step aside voluntarily, the Vice President and a majority of the Cabinet can send a written statement to Congress declaring that the President is incapable of holding office. If the President were to challenge such a resolution, Congress itself would vote on the question. The amendment also authorizes the President to appoint, and Congress to confirm, a new Vice President if a vacancy occurs in that office.
The four sections of the amendment deal with four possible situations in which the line of succession would need to be put into play. First, if the President dies or resigns, the VP takes over. Second, if there is no VP for one reason or another, the President nominates a new one, who has to be confirmed by Congress. Third, if the President declares that he cannot fulfill his duties for some period of time, the VP becomes Acting President. And finally, if it is decided (by “the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide”) that the President cannot do his job, the Vice President becomes Acting President until the President submits a written declaration that he can in fact do his job. If there’s disagreement about whether or not that’s the case, Congress gets to decide.
The amendment was soon put to the test.
An effort among some in Washington to push to have President Richard Nixon declared incapacitated prior to his resignation had not gone anywhere, but the scandals of the early 1970s did call for the use of the amendment as a means of replacing the Vice President. The resignation of embattled Vice President Spiro Agnew in late 1973 led Nixon to pick Gerald Ford to be his new Vice President, under the terms of the 25th—which was invoked once again only about a year later, when Nixon’s resignation put Ford in the White House, leaving the Vice Presidency open for Ford to name Nelson Rockefeller to the post.
Ronald Reagan would put the amendment to use as well, in 1985, when he declared that George H.W. Bush would be in charge while he was unconscious during a surgery. (George W. Bush did the same during his time in office.) And, to those worried about the consequences of Reagan’s place as the oldest President in U.S. history at the time of his election—a superlative he has since given up to Donald Trump—the Amendment offered a safety valve. One TIME columnist surmised in 1984 that, thanks to television, the world would “instantly” detect presidential infirmity in a way that would past ailing presidents managed to avoid.
The amendment has become newly newsworthy in recent weeks, as some opponents of President Trump, such as former George W. Bush speechwriter David Frum, have floated the idea that the Amendment could be used to declare that the President is “unable to discharge the powers and duties of his office.”
Though it is very unlikely that such an event might take place—the process for declaring a President incapacitated against his will is purposefully difficult—those who fought for its creation a half-century ago might be glad to hear that the American people know that, if the President were incapacitated, the steps to take are clear.
“By this thoughtful amendment, [the amendment’s advocates] have further perfected the oldest written constitution in the world,” Johnson said upon its ratification. “They have earned the lasting thanks of the American people, for whom it has so long secured the blessings of liberty.